Fiber laser device

Abstract

A fiber laser device 1 includes: a pumping light source 10 that emits pumping light; an amplification optical fiber 30 that amplifies and emits signal light by the pumping light; a detector 71 that detects a power of stimulated Raman scattering light generated from the signal light propagated through the amplification optical fiber 30 or the signal light emitted from the amplification optical fiber 30 in preference to a power of the signal light; and a controller 80 that controls a power of the pumping light based on the power of the light detected by the detector 71.

1 . A fiber laser device comprising:
 a pumping light source that emits pumping light;   an amplification optical fiber that amplifies and emits signal light of a single wavelength by the pumping light;   a detector that detects a power of a wavelength component of stimulated Raman scattering light generated from the signal light propagated through the amplification optical fiber or the signal light emitted from the amplification optical fiber in preference to a power of a wavelength component of the signal light; and   a controller that controls a power of the pumping light based on the power of the light detected by the detector.   
     
     
         2 . The fiber laser device according to  claim 1 , further comprising:
 a first mirror that is provided at one side of the amplification optical fiber to reflect the signal light; and   a second mirror that is provided at the other side of the amplification optical fiber to reflect the signal light at reflectance lower than that of the first mirror.   
     
     
         3 . The fiber laser device according to  claim 2 , wherein the detector is disposed at a side opposite to the amplification optical fiber using the first mirror as a reference. 
     
     
         4 . The fiber laser device according to  claim 3 , wherein the detector includes a light receiving portion that receives light transmitted through the first mirror, and
 the light receiving portion has light receiving sensitivity with respect to the wavelength component of the stimulated Raman scattering light higher than light receiving sensitivity with respect to the wavelength component of the signal light.   
     
     
         5 . The fiber laser device according to  claim 1 , further comprising a signal light source that emits the signal light incident on the amplification optical fiber. 
     
     
         6 . The fiber laser device according to  claim 1 , wherein the detector includes:
 a light branch portion that branches some of the light emitted from the amplification optical fiber; and   a light receiving portion that receives the branched light, and   the light receiving portion has light receiving sensitivity with respect to the wavelength component of the stimulated Raman scattering light higher than light receiving sensitivity with respect to the wavelength component of the signal light.   
     
     
         7 . The fiber laser device according to  claim 1 , wherein the detector includes:
 a light branch portion that branches some of the light emitted from the amplification optical fiber; and   a light receiving portion that receives the branched light, and   the light branch portion branches the wavelength component of the stimulated Raman scattering light in preference to the wavelength component of the signal light.   
     
     
         8 . The fiber laser device according to  claim 1 , wherein the detector includes:
 a light branch portion that branches some of the light emitted from the amplification optical fiber;   an optical filter that transmits the wavelength component of the stimulated Raman scattering light in preference to the wavelength component of the signal light, out of the branched light; and   a light receiving portion that receives the light transmitted through the optical filter.   
     
     
         9 . The fiber laser device according to  claim 1 , wherein the detector includes:
 a photothermal conversion portion that absorbs some of the light emitted from the amplification optical fiber and converts the absorbed light into heat; and   a temperature detector that detects a temperature of the photothermal conversion portion, and   the photothermal conversion portion is configured such that absorption efficiency of the wavelength component of the stimulated Raman scattering light is higher than that of the wavelength component of the signal light.   
     
     
         10 . The fiber laser device according to  claim 1 , wherein the controller controls the power of the pumping light to be small when the power of the light detected by the detector is equal to or greater than a predetermined magnitude. 
     
     
         11 . The fiber laser device according to  claim 10 , wherein the controller returns the power of the pumping light to an original power when the power of the light detected by the detector is smaller than the predetermined magnitude after the power of the pumping light becomes small. 
     
     
         12 . The fiber laser device according to  claim 10 , wherein the controller controls the power of the pumping light to be zero when the power of the light detected by the detector is equal to or greater than the predetermined magnitude. 
     
     
         13 . The fiber laser device according to  claim 12 , wherein the controller returns the power of the pumping light to an original power when the power of the light detected by the detector is smaller than the predetermined magnitude after the power of the pumping light becomes zero.